Impact of pH changes on neutral lipid production of the microalga Dunaliella tertiolecta isolated from Meke Crater Lake (Konya/Turkey)

In this study, the impact of a change in pH of the growth medium on the production of triacylglycerol (used as a biodiesel feedstock) and related parameters were evaluated in a green halophilic microalga Dunaliella tertiolecta. Microalgae were cultured in Johnson's nutrient medium with different initial pH values (pH = 4, 6, 8, 10) under suitable conditions for 25 days and growth was followed, triacylglycerol production and related parameters were analyzed. There was an increase in the growth rate, total chlorophyll and carotenoid contents, net oxygen production and consumption ratio did not show a significant change as accompanied by a remarkable increase of neutral lipid and triacylglycerol content of microalgae in proportion to a decrease in initial pH. On the other side, there was a decrease in the total chlorophyll and carotenoid content accompanied by a decrease in both oxygen production and consumption ration while there was no significant change in growth rate, neutral lipid, and triacylglycerol production of microalgae when the medium pH is adjusted as 10. Results show that lowering the initial pH of the growth medium might be used as a practical approach for induction of biodiesel feedstock production by Dunaliella tertiolecta